###### Abstract  
The attractive features of the direct AC-AC converters increase their use in many applications such as voltage control for a heavy-duty load that has a high time constant, AC machine drives, and heating systems based on the induction process. These converters process power in single-stage having simple circuit topologies with reduced switching devices and circuit components. These characteristics lead to the efficient power conversion process. The use of a low-frequency input transformer with multiple output tapping for the regulation of output voltage and frequency is one of the major sources of cost, size, and conversion losses. The complication in the switching algorithms is also the main concern in these converters. The preceding deficiencies lower their potency to be used in daily life. The costly controllers or processors are to be employed to realize the complex control techniques or algorithms. That increases the overall cost and circuit complication. This paper introduces the simple control techniques employed to a novel transformer less multi converter to have the various ac outputs for voltage and frequency regulation. The validation of power circuit and control schemes is tested through the simulation and practical results obtained in Simulink and practical setup respectively. multiconverter; voltage control; heaty-duty load; voltage and frequency regulation; control techniques 24 February 2021 25 March 2021 30 March  
approach is called direct AC-AC converters where the power conversion process is realized in a single conversion stage. In conventional indirect power converting approaches as in [1], the first stage is rectification that transforms the grid AC power to DC that is stored in a DC link capacitor. Then this DC power is transformed to AC power with required output characteristics. The main concern in this realization is a large count of switching and passive components. The number of switching devices is decreased in the indirect converters realized with three inverter legs as pinpointed in [2]. Here, both the rectification and inversion stage share the middle leg of the converter. This approach has low conversion losses as that of the four-leg converters with the same dc-link voltage and power quality. The power quality of the output voltage is improved in the three-leg converter by increasing the output voltage levels [3; 4; 5; 6]. These converting topologies are attractive as they have low switching voltage and improved power quality. But all these characteristics are ensured on the cost of circuit and control complication. The issues related to a dc-link capacitor are tackled in direct AC-AC converters. These power converting topologies lower the maintenance requirements and overall system losses. Their use becomes more valuable for load or grid voltage control as they are realized with a lower number of switching units. The use of external power storage devices is also eliminated in their realization [7; 8]. The direct AC-AC circuit may be realized with basic DC-DC topologies that include the buck, boost, or buck-boost. The merits of these topologies include simple circuit and control schemes but there are commutation issues due to the use of bidirectional or AC switches [9]. This problem may be tackled either by connecting the RC protection circuit across the switching units or by employing soft commutation techniques. The power losses in the RC circuit degrade the power quality of the output as they distort the outputs. The use of RC protection circuits is eliminated in some novel AC-AC power converting topologies as reported in [10; 11]. But these topologies lack bipolar voltage characteristics so they can only be employed to resolve either voltage sag or swell issues. They cannot be employed as frequency controllers. Z-source structure is employed in [12; 13] to ensure both polarities of the output voltage but their realization has certain drawbacks including abrupt change in voltage.